The present invention relates to a control apparatus for a linear motor used for driving a pickup of an information storage/readout apparatus.
In information storage/readout apparatuses, a pickup for storing information into and for reading information from a disk-shaped storage medium (referred to simply as a disk hereafter) is supported by a slider which is mounted linearly movably in a radial direction of the disk. A driver is provided for the slider in the form of a rotary motor whose rotational driving force is transmitted to the slider by means of a reduction mechanism, for example, a combination of a rack and a pinion. However, a rotary motor has limited response characteristics, which imposes inherent limitations in a so-called high speed search operation in which the pickup is driven at a high speed to search for a desired recorded track.
Despite such technical difficulties, search operations of even higher speed are demanded, and a linear motor which exhibits good response characteristics has been employed recently as a driving source for the pickup to achieve higher speeds in search operations.
On the other hand, a linear motor is arranged in such a way that motion of a movable portion is braked only by mechanical frictional force between a guide rail and the movable portion moving along the guide rail. Thus, if the pickup is to be driven directly by the linear motor, it is difficult to position the pickup accurately on the desired track even though the pickup may be driven at a high speed. This problem requires solution.